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Abstract

The rate that nitrogen is becoming available to plants has been increasing in
recent years. Plant species diversity decreases with an increased enrichment of nutrients
to the environment. One level in which plants could be affected by the increase in
nutrient availability is in their roots. Mycorrhizal colonization is important for a plant's
uptake of nutrients from the soil. We set out to find if nitrogen fertilization has an effect
on the arbuscular mycorrhizae (AM) fungal colonization in two species of plants.
Twenty four individuals each of Daucus carola and Agropyron repens were sampled and
analyzed for AM association in both fertilized and non-fertilized plots. One would
expect to find that when nitrogen fertilization occurs the AM associations would decrease
because more nitrogen would be available for the plant to uptake directly from the roots.
We observed that there were no significant differences in AM colonization between the
nitrogen fertilized and non-fertilized plants. However, we found that there were
significant differences in the number of total structures found between the two species.
A. repens had more total structures counted than D. carola. We observed that perennial
grasses made more AM associations than biennial forbs. There were also some
significant differences in the specific AM structures that colonized the plants. Both
species had more vesicles than other structures and hyphae were the structures counted
the least. The plants could be allocating more resources to storage as a result of the
higher levels of vesicles. Future studies should be made to look further into the dynamics
of these associations in agricultural crops.